In recent years the connection of metal couplings has been achieved by reducing the diameter of a metal sleeve (ferrule) over the end of a hose which has been pushed onto a coupling tail. This is achieved with the metal in a “cold state” which has meant, along with the ability to maintain continuity in the case of hydraulic transmission hoses at extreme pressures, that high radial loads are required, to effect the required deformation of the metal sleeve (ferrule).
Also, as the ferrule, hose and tail assembly are produced with various densities or structures along their axial length and the subsequent compression of the total assembly has meant the final “swage” was not cylindrical but tapered. This has required that the machinery not only be strong but also extremely rigid.
There are various designs of swage presses able to achieve this function. All employ some method of “wedging” one component against another to bring typically eight elements (shoes) radially in from one diametrical arrangement to another. By far the most popular and the most economical to manufacture swage press has been the “cone/shoe” type arrangement. A view of such a swage press machine part is depicted in FIG. 1 of the drawings annexed hereto.
In FIG. 2 and FIG. 3 of the annexed drawings, further sectioned views of the swage press machine part shown in FIG. 1 (usually termed “head assembly”), the various working elements are shown. It can be seen that should hydraulic pressure be applied to the rear of the operating piston that the operating piston will move forward. As the piston has a cone shape in its internal formation, and this cone shaped formation bears onto the shoe elements which are in turn wedged against the front plate or flange, these shoe elements will be driven inwards creating “pallets” of an ever decreasing cylindrical arrangement.
As can be seen in FIG. 4 of the annexed drawings, the housing element is manufactured as a single element. In the assembly of this arrangement, the operating piston is inserted from the front, the shoe cluster is then inserted and finally the front plate or flange is bolted onto the front of the housing. All current machines of this type are produced in this manner.
A weakness in this design is that if say the operating piston produces 100 tonne of force, then the front plate or flange must be able to withstand the same amount of reactive force. The quality of the swaging process and the ultimate performance and rigidity of the machine is due largely to the design and ultimate performance of the front plate or flange. As bolts are commonly used to retain the front plate or flange onto the housing, these bolts must also provide a reactive moment as well as the reactive axial force to resolve the out of alignment force of the shoe elements.
Using too many retaining bolts produces a weakness in the front plate or flange as the flange will flex more if there are more retaining bolt holes. The amount of bolt holes acts as a “perforation” and causes a weakness in an area where the highest moment forces exist. In reality, the minimum amount of bolts are used to achieve a 2:1 safety margin in order to achieve the stiffest possible front plate or flange, the least amount of flex and ultimately the highest performance and quality swage possible.
One further serious flaw with existing designs such as those shown in FIGS. 1 to 4, is that in a number of cases, due to incorrect component selection and/or human error in regard to the torque applied to the bolts, catastrophic failure has occurred providing significant health and safety risks to operators who operate the swage press from the front as is usually the case. Such failures in some cases have included having the bolts breaking and firing at high velocity towards the operator.